Integration of risk variants from GWAS with SARS-CoV-2 RNA interactome prioritizes FUBP1 and RAB2A as risk genes for COVID-19

The role of host genetic factors in COVID-19 outcomes remains unclear despite various genome-wide association studies (GWAS). We annotate all significant variants and those variants in high LD (R2 > 0.8) from the COVID-19 host genetics initiative (HGI) and identify risk genes by recognizing genes intolerant nonsynonymous mutations in coding regions and genes associated with cis-expression quantitative trait loci (cis-eQTL) in non-coding regions. These genes are enriched in the immune response pathway and viral life cycle. It has been found that host RNA binding proteins (RBPs) participate in different phases of the SARS-CoV-2 life cycle. We collect 503 RBPs that interact with SARS-CoV-2 RNA concluded from in vitro studies. Combining risk genes from the HGI with RBPs, we identify two COVID-19 risk loci that regulate the expression levels of FUBP1 and RAB2A in the lung. Due to the risk allele, COVID-19 patients show downregulation of FUBP1 and upregulation of RAB2A. Using single-cell RNA sequencing data, we show that FUBP1 and RAB2A are expressed in SARS-CoV-2-infected upper respiratory tract epithelial cells. We further identify NC_000001.11:g.77984833C>A and NC_000008.11:g.60559280T>C as functional variants by surveying allele-specific transcription factor sites and cis-regulatory elements and performing motif analysis. To sum up, our research, which associates human genetics with expression levels of RBPs, identifies FUBP1 and RAB2A as two risk genes for COVID-19 and reveals the anti-viral role of FUBP1 and the pro-viral role of RAB2A in the infection of SARS-CoV-2.


Annotation of significant variants for COVID-19
GWAS data for COVID-19 were collected from the COVID-19 host genetics initiative (HGI) (https:// www.covid 19hg.org/) 24 .We used meta-analyzed COVID-19 data sets (phenotypes A2: critically ill vs. population, phenotypes B2: hospitalized COVID-19 vs. population, and phenotype C2: COVID-19 vs. population) from the eighth April 2022 release of COVID-19 Host Genetics Initiative including European ancestries provided by 23andMe (https:// www.covid 19hg.org/ resul ts/ r7/).We used a p-value threshold of 5 × 10 −8 to hit significant variants.PLINK v1.9 (http:// pngu.mgh.harva rd.edu/ purce ll/ plink/) 25 was used to find high LD variants (R 2 > 0.8) from the European population of 1000G project GRCh38 phase 3 release data in Ensembl 26 .We then used the Variant Effect Predictor (VEP) 27 to annotate all significant variants and those variants in high LD with them.The annotated variants were classified into coding and noncoding regions.Coding regions were further divided into synonymous and nonsynonymous mutations.We recognized genes intolerant nonsynonymous mutations in coding regions.The human lung eQTL data shown in this study were obtained from the Genotype-Tissue Expression (GTEx) Portal (dbGaP Accession phs000424.v8.p2) 28 which contained data for 515 lung samples.We took the intersection between our hit non-coding variants and variants with eQTLs.We then identified genes regulated by the overlapping variants as eGENEs in the lung.Direct downloads of the cis-eQTL figures were made from the GTEx Portal.

GO enrichment analysis
We conducted GO enrichment analysis of the union of RBP-encoding genes with nonsynonymous mutations and eGENEs using clusterProfiler v4.4.4 R package 29 .The treeplot function of Enrichplot v1.16.2 was used to cluster GO terms 30 .

Collection of the human SARS-CoV-2 interactome
To identify total host RBPs interacting with SARS-CoV-2 RNA, we collected data from six studies on multiple cell lines using different approaches [31][32][33][34][35][36] .We manually excluded RBPs of other species and took a union of 503 human RBPs from these studies.

Transcription factor binding motif analysis.
We investigated functional COVID-19-associated variants for their potential effect on TF binding affinity using models from JASPAR2022 core collection 46 and TFBSTools v1.34.0 47 .We defined a score threshold of 80% and a p-value of 5.00 × 10 −3 to confirm the occurrence of the TF motif for any of the two alleles.DNA input of NC_000008.11:g.60559280T>Cwere 'TTG CTG TGC AAG CCA TTT CCC CGT TTC ATG T' and 'TTG CTG TGC AAG CCA CTC CCC GTT TCA TGT ' and NC_000001.11:g.77984833C>Awere 'GTA GTT TCA CAC AAA CTT TTC TTA GAA TAT C' and 'GTA GTT TCA CAC AAA ATT TTC TTA GAA TAT C' .We used ggseqlogo v0.1 48 to visualize the motif of target TFs, and NC_000001.11:g.77984833C>Awas displayed in the negative strand.

Correlation analysis between candidate TFs and RBPs
Gene expression data shown in correlation analysis were obtained from the genotype-tissue expression (GTEx) Portal (dbGaP Accession phs000424.v8.p2) 28 containing data for 515 lung samples.We then used ggstatsplot v0.11.0 to display the correlation matrix and ggcorrplot v0.1.4to visualize the scatterplot of candidate TFs and RBPs 49 .

Identification of COVID-19 associated variants and risk genes
Despite various GWAS mapping risk loci for COVID-19, the interpretation and mechanism underlying the study remain unknown.To gain a broader view of how genetic variants influence the susceptibility and severity of COVID-19, we took the location and consequences of risk variants into consideration (Fig. 1a).To interpret the results from HGI comprehensively, we found LD variants (R 2 > 0.8) of significant SNPs (p < 5 × 10 −8 ) and used the Variant Effect Predictor (VEP) to annotate all these variants (Supplementary Table 1) in European ancestry group (phenotype A2: critically ill vs. population, phenotype B2: hospitalized COVID-19 vs. population, and phenotype C2: COVID-19 vs. population).In these three phenotypes, about 4 % of variants were found in coding regions, while 96% were found in non-coding regions (Fig. 1b).In coding regions, we focused on genes intolerant nonsynonymous mutations.To further understand the potent target genes in non-coding regions, we surveyed eQTL in GTEx 28 in lung tissue to identify genes whose expressions are associated with variants (eGENEs).Risk variants and variants with eQTLs were intersected, and the targeted genes regulated by eQTLs were defined as eGENEs.Overlapping genes intolerant nonsynonymous mutations, and overlapping eGENEs across three phenotypes were described in Supplementary Fig. 1a and b, respectively.The overlap of genes intolerant nonsynonymous mutations and eGENEs across three phenotypes was depicted in Fig. 1c.We then performed GO analysis on all target genes (genes intolerant nonsynonymous mutations and eGENEs) of COVID-19 to determine their overall biological function (Supplementary  After identifying potential risk genes for COVID-19, it is crucial to associate host genetic factors with SARS-CoV-2 to illustrate the disease's mechanism.As SARS-CoV-2 is an RNA virus, RBPs are one of the most direct ways the host interacts with the virus.Several studies have been conducted to examine the interaction between host proteins and RNA of SARS-CoV-2, to identify the host RBPs that directly bind SARS-CoV-2 RNA and furnish proof of the roles RBPs play in the infection process of SARS-CoV-2.In the previous six studies [31][32][33][34][35][36] (Supplementary Table 3), 503 host RBPs interacting with SARS-CoV-2 RNA have been identified in multiple human infected cell lines using different RNA-centric cross-linking approaches (Supplementary Fig. 2a).As it is shown in Supplementary Fig. 2a, these in vitro results have shown differences in identifying the SARS-CoV-2 RNA interactome, possibly due to RNA-centric procedures and different cell contexts.GO analysis has showed that host RBPs participated in multiple steps of the SARS-CoV-2 life cycle (Supplementary Fig. 2b,c).
We surveyed the 503 RBPs to determine whether the risk genes described above function in interacting with SARS-CoV-2.We observed that risk genes RAD50 double strand break repair protein (RAD50), Far Upstream Element Binding Protein 1 (FUBP1), and RAB2A, member RAS oncogene family (RAB2A), were RBPs that interacted with SARS-CoV-2 RNA.We then identified risk variants that regulate the expression of RBPs from GWAS statistics, all located in non-coding regions (Table 1).We assumed that these polymorphic loci participate in COVID-19 by affecting the expression of RBPs.
In chromosome 1, we identified two genetic variants as cis-eQTLs associated with the eGENE FUBP1 in the lung for hospitalization.NC_000001.11:g.77501822T>A is located in the AK5 locus downstream FUBP1, while NC_000001.11:g.77984833C>A is located upstream FUBP1.We found that risk allele carriers of the lead SNP NC_000001.11:g.77984833C>Ahad a significantly higher risk of worse disease outcomes than non-carriers (MAF = 0.1191, beta = 0.092186, p = 3.41 × 10 −9 ).Fig. 2d shows that this risk allele was linked to a lower level of FUBP1 expression in the lung.These results demonstrate that NC_000001.11:g.77501822T in FUBP1 is linked to a higher rate of SARS-CoV-2 hospitalization and downregulates the expression of FUBP1 in the lung, which may limit FUBP1 anti-viral activity and thereby contribute to the development of the SARS-CoV-2 infection.
In chromosome 5, we identified sixteen and four genetic variants that increased the risk of severity and hospitalization of COVID-19, respectively.These variants were located within a region of strong LD and were cis-eQTLs associated with eGENE RAD50.GWAS analysis indicated that the lead SNP NC_000005.10:g.132457732dup(MAF = 0.1141, beta = 0.1129, p = 6.33 × 10 −9 ) for the A2 phenotype and NC_000005.10:g.132448315C>T(MAF = 0.1129, beta = 0.081636, p = 1.96 × 10 −8 ) for the B2 phenotype upregulated the expression of RAD50 in the lung (Fig. 2b,f).These findings suggested that this locus is a risk

FUBP1 and RAB2A are expressed in the SARS-CoV-2-infected epithelial cells of nasopharynx in COVID-19 patients
After identifying risk variants for COVID-19 which regulate the expression level of RBPs, it is necessary to validate the expression of interested RBPs in SARS-CoV-2 targeted tissue and infected cells to provide evidence for the interaction between our interested RBPs and SARS-CoV-2 RNA due to heterogeneity in identifying the SARS-CoV-2 RNA interactome from different RNA-centric procedures and different cell contexts (Supplementary Fig. 2).
To investigate the expression of our targeted RBPs, we first chose single-cell RNA sequencing (scRNA-seq) data of COVID-19 patients from the integrated Human Lung Cell Atlas (HLCA) 51 , a large-scale, cross-dataset scRNA-seq of the lung.The COVID-19 patients scRNA-seq data from HLCA included 60 samples and 49 cell types (Fig. 3a).We found that FUBP1 and RAB2A were expressed in multiple cell types, such as club cells, brush cell of the tracheobronchial tree, and epithelial cell of alveolus of lung while RAD50 was expressed lowly in almost all cell types (Fig. 3b-d).
To further examine the manifestation of targeted RBPs in cells that have been infected, we chose another scRNA-seq data from nasopharyngeal samples because SARS-CoV-2 infection primarily affects the upper respiratory tract 52 .We analyzed scRNA-seq data from COVID-19 patients reported by Ziegler CGK et al. 53 and annotated cell types coarsely due to the limited number of cells identified as positive for SARS-CoV-2 RNA (vRNA + ) (Supplementary Fig. 3b).Marker genes were shown in Supplementary Fig. 3a.We demonstrated the top four epithelial cells (secretory cells, ciliated cells, squamous cells and FOXN4 + cells) with a high percentage of vRNA + cells (Supplementary Fig. 3c, Fig. 4a) to display the most possible SARS-CoV-2-infected epithelial cells.The results showed that FUBP1 and RAB2A are expressed in several types of nasopharyngeal epithelial cells, including FOXN4 + cells, squamous cells, ciliated cells, and secretory cells, in the upper respiratory tract of COVID-19 patients, especially the vRNA + group (Fig. 4c,d).Notably, FUBP1 and RAB2A were highly expressed in vRNA + ciliated cells (Fig. 4b), which were the primary target cells of SARS-CoV-2 upon infection 54 .Similar to the result from HLCA, RAD50 was low expressed in epithelial cells (Fig. 4b, Supplementary Fig. 3d).
These findings show that FUBP1 and RAB2A are expressed in SARS-CoV-2-infected epithelial cells, which lays the foundation for the interaction between SARS-CoV-2 RNA and our targeted RBPs, indicating that FUBP1 and RAB2A may play essential roles in the infection of SARS-CoV-2.

Functional variants that regulate the expression of FUBP1 and RAB2A
Since COVID-19 risk variants regulating RBPs are all in non-coding regions, it is challenging to identify the causal variants.Reports suggest that non-coding variants can potentially regulate the expression of target genes by either disrupting the underlying TF binding sites or altering the strength of regulatory regions 58,59 .
To identify the likely causal variants and explore the genetic mechanisms driving COVID-19 hospitalization risk, we first surveyed the ADASTRA database v5.1.2 43,55, which identified allele-specific TF binding at SNPs in Chromatin Immunoprecipitation Sequencing (ChIP-Seq) data.After analyzing all hit variants and those in high LD with the lead SNPs in the ADASTRA database v5.1.2 43,55, we found that NC_000008.11:g.60559280T>C,which was highly linked with lead SNP NC_000008.11:g.60515641C>Tmapped to RAB2A, is an allele-specific binding site for twelve TFs (Supplementary Table 4), which made us prefer NC_000008.11:g.60559280T>Cas a functional variant.Using the scRNA-seq described above, we examined the expression of SPI1 and ELF1, which concordantly matched motif analysis and were more credible.It was observed that ELF1 exhibited a higher expression level (Supplementary Fig. 4a), leading us to recognize ELF1 as the effector TF, whose binding affinity was altered in NC_000008.11:g.60559280T>C(Fig. 5a).Correlation analysis showed that ELF1 was positively associated with RAB2A (Supplementary Fig. 4e), which correlates with its transcriptional function 56 .We then used TFBStools 47 to predict the binding affinity of ELF1 on the reference and alternative alleles of NC_000008.11:g.60559280T>C.The  www.nature.com/scientificreports/p-value changed from 6.40 × 10 −3 (allele T) to 1.17 × 10 −3 (allele C), so the binding affinity increased in the risk allele.Surveying epigenomic data in the lung, we found NC_000008.11:g.60559280T>Clocated in an activated lung enhancer region through epigenomic data (Fig. 5a), which demonstrated the transcriptional activity of NC_000008.11:g.60559280T>C.The result shows that the risk allele of NC_000008.11:g.60559280T>C,which is highly linked to NC_000008.11:g.60515641C>T, is connected to higher transcription levels of RAB2A and is believed to potentially strengthen the binding affinity towards ELF1, a transcriptional activator.
For variants mapped to FUBP1, which did not hit the ADASTRA database, we assumed that the variants were more likely functional if located within active lung CREs.We surveyed the regulatory regions in the lung and found NC_000001.11:g.77984833C>Alocated in the enhancer regions of FUBP1 (Fig. 5b), so we identified this variant as the functional variant.We then performed TF analysis on NC_000001.11:g.77984833C>Aby TFBStools 47 .We used all version models from JASPAR2022 core collection 46 and set the variant ±15bp as input (detailed in the method).We then defined a score threshold of the TFs as 80% and p-value as 0.005 to confirm the occurrence of the TF motif for both reference and alternative alleles (Supplementary Table 5).We found 12 candidate TFs whose binding affinity changed at NC_000001.11:g.77984833C>A.We also investigated the expression of the candidate TFs in the scRNA-seq described above (Supplementary Fig. 4a).We then performed correlation analysis between these highly expressed TFs and FUBP1, and the activator MEF2A 57 was positively associated with FUBP1 (Supplementary Fig. 4f), which correlated with its transcriptional function, so we identified MEF2A as the effector TF.The transcription of FUBP1 was anticipated to be lowered by the risk allele (A) of NC_000001.11:g.77984833C>A.The binding affinity of the transcriptional activator MEF2A was predicted to decrease at NC_000001.11:g.77984833C>A.The results show that activator MEF2A binds more weakly in the risk allele of NC_000001.11:g.77984833C>A,thus reducing the transcription of FUBP1 and leading to more hospitalizations.
Through the strategy mentioned above, we identify two functional variants that regulate the expression of FUBP1 and RAB2A by changing TF binding affinity, respectively.NC_000008.11:g.60559280T>C,located in an activated enhancer region of RAB2A, upregulates RAB2A expression by increasing the affinity of the activator www.nature.com/scientificreports/ELF1, while NC_000001.11:g.77984833C>A,located in the enhancer regions of FUBP1, downregulates FUBP1 expression by decreasing the binding affinity of the activator MEF2A.

Discussion
Genetic variants have been discovered to predispose COVID-19 patients to a more severe outcome, such as hospitalization.The interpretation of GWAS is vital for understanding the mechanisms underlying COVID-19.
We annotated all variants and those variants in high LD (R 2 >0.8) and classified them as coding and non-coding variants.We further identified risk genes from genes with nonsynonymous mutations and eGENEs in the lung.To investigate how these risk genes function in COVID-19, we took RBPs, which have been recognized to engage in multiple stages of the SARS-CoV-2 life cycle, into consideration and identified three RBP-related loci for COVID-19.Subsequently, we demonstrated the expression levels of FUBP1, RAD50, and RAB2A in epithelial cells infected with SARS-CoV-2 in scRNA-seq data and speculated that RAD50 might not function in the lung because of its low expression.We further chose an allele-specific strategy and identified NC_000001.11:g.77984833C>Aand NC_000008.11:g.60559280T>Cas functional variants.TF binding affinity changed at these two variants contributed to the hospitalization of COVID-19 through downregulating and upregulating the expression of FUBP1 and RAB2A, respectively.These results led us to identify FUBP1 and RAB2A as susceptible genes for the hospitalization of COVID-19 and to reason that FUBP1 played an anti-viral role while RAB2A played a pro-viral role in the infection of SARS-CoV-2.FUBP1 is a canonical RBP that belongs to a conserved family of single-stranded (ss) DNA-binding regulators named FUBPs 58 .Although FUBP1 is primarily located in the nucleus, reports suggest it can also be expressed in the cytoplasm, where it regulates cytoplasmic virus RNA 59 .Researchers found that FUBP1 was downregulated significantly in COVID-19 patients compared to healthy controls in peripheral blood monocytes 60 , consistent with our finding in lung tissue.Although little is known about the function of FUBP1 in COVID-19, evidence has shown that FUBP1 suppresses protein translation of Japanese encephalitis virus (JEV) by targeting its 5' and 3' UTR 61 .Since FUBP1 binds to SARS-CoV-2, we propose that FUBP1 functions in an anti-viral way by suppressing transcription or protein translation.It has been validated that FUBP1 binds to the negative-sense of 29534-29870 in SARS-CoV-2 RNA (ORF10, 3'UTR, and poly(A)) in Calu-3 cells and might play a transcription role 62 .We speculate that FUBP1 functions in an anti-viral way by binding to ORF10 and 3'UTR of the negative strand in SARS-CoV-2 RNA and repressing the transcription of SARS-CoV-2.It is promising to target FUBP1 in the treatment of COVID-19 since a study has found that FUBP1 was repressed after SARS-CoV-2 infection in Calu-3 cells, and expression of FUBP1 could be reversed after allicin exposure to SARS-CoV-2-infected cells 63 .
RAB2A is a Rab family member and was first identified as a novel RBP in 2018 64 .Though little is known about its function on virus RNA, the role of RAB2A has been well illustrated as a critical modulator of intracellular membrane trafficking, especially in protein transport in ER-Golgi intermediate compartment (ERGIC) 65,66 .Knockdown of RAB2A induces Golgi fragmentation in HeLa-S3 cells 65 .RAB2A may play an essential role in ERGIC, where structural and non-structural proteins are assembled and transported to the cell surface and other organelles 9,67 .SARS-CoVs have been reported to exploit the intermediate compartment (IC) as an intracellular site of formation 68 .SARS-CoV-2 may hijack the host early secretory pathway involving RAB2A to assemble and transport.Moreover, RAB2A plays a vital role in the fusion of lysosomes (LYSs) and late endosomes (LEs) 69 .It has been found that RAB2A interacts with NSP7 and ORF3a 70,71 .ORF3a may bind to RAB2A and inhibit the fusion of LEs and LYSs through interaction with RAB2A, thus impairing the formation of autophagolysosomes.Moreover, a CRISPR screen in Huh-7.5 cells infected with SARS-CoV-2 showed that RAB2A was critical for virus replication and virus-induced cytopathic effect (CPE), indicating its significance in virus replication 70 .Considering that RAB2A has been identified as a SARS-CoV-2 binding protein, we put forward another assumption that SARS-CoV-2 hijacks RAB2A to facilitate the replication of its genome.Recent studies have shown that RAB2A interacts with NSP7 of SARS-CoV-2 70 , which is an indispensable co-factor binding to NSP12 to form an RdRp complex and plays a vital role in the stabilization of NSP12 regions involved in RNA binding 72 .We reason that RAB2A might contribute to stabilizing SARS-CoV-2 RNA by forming a complex where RAB2A binds to both vRNA and NSP7, thus facilitating the replication of SARS-CoV-2.Consistent with our study, a meta-analysis of GWAS revealed that RAB2A (rs13276831) was associated with severe COVID-19, and more expression of RAB2A was associated with worse disease 73 .In addition, a Mendelian randomization analysis based on transcriptome-wide summary data associated RAB2A with hospitalized COVID-19 in Artery Tibial 74 .Strong evidence from genetic variants near protein-encoding loci (cis-pQTL) analysis combined with GWAS also suggested that RAB2A was a possible causal gene for severe COVID-19 75,76 .These studies verify the results of our research.Searching for the ChEMBL database, we identify CID1067700 as a promising inhibitor of RAB2A, which has also been shown to block Arf-like small GTPase Arl8b that regulates SARS-CoV-2 egress 77 .Further experiments are required to explore the effectiveness of CID1067700 in targeting RAB2A in treating COVID-19.
Even though few potential drugs have been found to target FUBP1 and RAB2A, using RNA-binding proteins to treat COVID-19 is still promising.Researchers have found pioglitazone and lapatinib as potential drugs since pioglitazone decreases the expression of RPS3, eIF4B, and RPS10, while lapatinib decreases the expression of EEF1A1, EIF5A, and RPS10 RBPs 78 .Another study investigated drugs targeting the interacting proteins of SARS-CoV-2-related RBPs and identified Doxorubicin and Topotecan as possible drugs targeting protein interactome of RBPs 79 , providing another way to use RBPs in the treatment of COVID-19.
Our data mining study identified two RBPs as susceptible genes for hospitalization of COVID-19.However, we failed to identify the exact binding sites of RAB2A on SARS-CoV-2 RNA due to limited CLIP-seq data.Further investigations, including RNA Binding Protein Immunoprecipitation Assay Sequencing (RIP-seq) and Gel Shift Assays (EMSA) are warranted to determine the exact binding sites of FUBP1 and RAB2A on SARS-CoV-2 thus to analyze the effects of variations of SARS-CoV-2 RNA on the binding sites.We also did not explain the further mechanism by which NC_000001.11:g.77984833C>Aand NC_000008.11:g.60559280T>Cregulate the expression level of FUBP1 and RAB2A, respectively.CRISPR-mediated inhibition (CRISPRi) and activation (CRISPRa) could be used to validate the genetic effects of these two variants on RBPs, and ChIP-Seq (or ChIP-qPCR) could investigate the binding affinity of TFs.It remains unclear how FUBP1 and RAB2A function in SARS-CoV-2 infection.Further studies such as CRISPR are needed to clarify in which process the anti-viral role of FUBP1 and the pro-viral role of RAB2A play in COVID-19.
In summary, this study annotates risk genes from genetic variants by combining variant function and cis-eQTL and delves into the interaction between host RBPs and SARS-CoV-2.This study identifies two key contributing genes, FUBP1 and RAB2A, whose corresponding proteins bind to the genome of SARS-CoV-2 in SARS-CoV-2-infected epithelial cells in the lung.This study also highlights that two functional variants regulate the expression of these two RBPs by altering the binding affinity of TFs, indicating the anti-viral role of FUBP1 and the pro-viral role of RAB2A.This study provides valuable insights into the genetic risk genes in the pathogenesis of SARS-CoV-2 and provides compelling evidence for further investigations into the role of FUBP1 and RAB2A as RBPs in SARS-CoV-2 infection.The study proposes a model that suggests host variants may change the TF binding affinity, thereby altering the expression levels of RBPs and influencing the function of RBPs interacting with the virus (Fig. 6).The findings offer novel perspectives in the realm of RNA virus research, particularly with regards to the interaction between host RBPs and viral RNA.

Figure 1 .
Figure 1.Atlas of potential risk genes for COVID-19 (a) Flowchart of the study design.(b) Distribution of genomic regional categories for COVID-19 variants.(c) Vennplot of genes intolerant nonsynonymous mutations and eGENEs.(d) Clustered GO terms of all potential risk genes for COVID-19.

Figure 3 .
Figure 3. Expression of FUBP1, RAD50, and RAB2A in single-cell data in COVID-19 patients from HLCA.(a) UMAP of cell types of single-cell data in COVID-19 patients from HLCA.(b) The Feature plots showing the expression levels of FUBP1, RAD50, and RAB2A in COVID-19 patients.(c) Dotplot and (d) Violin plot showing the number of cells expressing FUBP1, RAD50, and RAB2A in COVID-19 patients.

Figure 4 .Figure 5 .
Figure 4. Expression of FUBP1, RAD50, and RAB2A in single-cell data in the nasopharynx.(a) UMAP of the top four epithelial cells with a high percentage of SARS-CoV-2 RNA + (vRNA + ) cells in the nasopharynx.(b) Dotplot showing the number of cells expressing FUBP1, RAD50, and RAB2A in both vRNA + and SARS-CoV-2 RNA − (vRNA − ) groups.The dots with yellow frames indicate expression levels of FUBP1 and RAB2A in ciliated cells, which SARS-CoV-2 enters in airway epithelia immediately upon infection 54 .The feature plots show the expression levels of (c) FUBP1 and (d) RAB2A in the four epithelial cells, which are grouped by SARS-CoV-2 RNA status.(e) The violin plot of FUBP1 and RAB2A expressed in epithelial cells, grouped by SARS-CoV-2 RNA status.

Figure 6 .
Figure 6.Hypothesis model of risk variants mapped to RBPs predispose hospitalization of COVID-19.MEF2A strongly binds to the non-risk allele of FUBP1 and ELF1 weakly binds to that of RAB2A, which enhances the anti-viral ability of FUBP1 and reduces the pro-viral capacity of RAB2A, leading to less virion.In contrast, MEF2A weakly binds to the risk allele of FUBP1, and ELF1 strongly binds to that of RAB2A, which reduces the anti-viral ability of FUBP1 and enhances the pro-viral capacity of RAB2A, leading to more virion and worse outcome of COVID-19.